planemo

Noun.  (astronomy) an astronomical object with enough mass to achieve hydrostatic equilibrium, but not enough initiate core fusion at any time in its existence. That is, it is rounded in shape and is smaller than a star. Planemos include planets, dwarf planets, and the larger moons of the Solar System, but also sub-brown dwarfs and rogue planets between the stars. The upper limit of a planemo is estimated to be 13 times the mass of Jupiter (4,000 times that of the Earth, or 1ΒΌ% the Sun); the smallest known planemo in the Solar System is Mimas, 6 millionths the mass of the Earth.

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This entry was last updated on RefTopia from its source on 3/20/2012.